QSC approaching 5000 hours, major maintenance?

[Andre Huizing]

Hello experts,

Our QSC8.3 490hp 2006 vintage just passed 4000 hours and I hear some people saying that 5000 hours is some “milestone” when major maintenance should be in order? I know Cummins is prescribing a valve adjustment at 5000 hours (which seems a huge amount to me for this but who am I to judge). Some info on our installation:

• single engined full displacement trawler;
• semi live aboards, engine runs regularly most of the year over the last 8 years (before that little use);
• slow revving, typically between 1100 and 1500 (displacement speeds between 6 and 8 knots);
• always used ULSD fuel;
• oil/filter changes every 300 – 400 hours (Cummins says 250 and double that when using ULSD);
• never had major issues, runs fine, no smoke, uses no measurable oil between changes, gets just above its rated rpm;
• Last 8 years on salt water. Coolers get regular maintenance. Engine is flushed with fresh water when expected stationary period exceeds 2 weeks.

Question is: should I be expecting/doing major maintenance jobs around the 5000 hours mark?

Cheers, André Huizing

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[Andre Huizing]

Thanks for the tips Tony. Most is still original except for the seawater pump and engine mounts (both replaced this year). As said we run >95% of time around 1300 rpm which in our case is 3 – 4 GPH.

I keep an eye on the belt (approx. 3 yo). Seems fine but creates quite a bit of dust.

We have conventional shaft drive through TwinDisc MG5091SC transmission. No ZEUS.

Cheers, André

[Tony Athens]

Valves ,  run thru them twice, “everything that spins” on the front of the engine including the belt, seawater pump?? (if the internals are original,   and the aftercooler if not on the bench  the last 2 years.. Overall you have to be the judge as to how deep you want go go. Your fresh water flush regiment is a major key with all

On QSCs that run hard (on plane 25% of the time above 15 GPH)  & we generally watch over them, they usually start nit-picking the owners at about 5000 hrs 

Your ZEUS drives–any overall comments?

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